The present invention is directed to metal seals for use in a well head such as between the head and the casing, between the hanger assembly and the head, and between the hanger assembly and the tubing head adapter.
Resilient seals are presenting a problem in well heads, especially, in high temperature gas service and other environments such as high H2S and CO2 content mixed with high temperature and pressure. The industry has been asking for tubing head metal seals and more recently casing metal seals. The present metal seals have many problems. A partial list of these problems are high cost, close tolerance, fine finishes, tolerance accumulation, one-directional seal, problems holding gas, seals can be used only once, need multiple seals or shims, not enough energy to effect the metal seal, etc.
The present invention is an economical, bidirectional seal that is very reliable and will hold high or low pressure gas as well as liquids. The seal ring requires neither close tolerances nor fine finishes and it incorporates a tolerance adjustor so that only one size seal is needed. The seal can be used more than one time if needed in the field and if there is a leak, the seal can be effected by manipulation of the tolerance adjustor to effect more squeeze, thus requiring no outside help or additional parts to make a seal.
The present invention is also directed to providing means for preventing the well casing from expanding in a longitudinal direction and breaking the integrity of the casing metal seal and other seals and/or unseating the casing hanger.
And in addition, the present invention is directed to providing a fire resistant well head by providing a well head system with all metal seals.